No.
Dreams Unlimited is a
travel agency. They have full access to Disney's room reservation system and a staff of experts in dealing with Disney vacation planning. Given the feedback you will often read about bookings direct with CRO (Disney), it's probably not a stretch to say that DU's people often know more about Disney and its resorts than Disney's own staff.
There is no obligation for getting a quote from DU. I've never booked a trip through them, but did get quotes on a couple of trips that we had considered in the past. They were very prompt, very professional, and did a great job of applying whatever discount codes existed for my travel dates.